There is this idea that the game somehow forces you to play with the Viking Race for the first island(s). This is quite simply not true. We have other units that we can use and they are quite good. I'll give some examples : There are bears, ancient bears, snakes, spiders, wolfs... as you can see there's many units to choose from on the first island.
I even tested to see if I can complete the first island with other units then Viking Units and I can confirm that it can be done!
So no, we're not forced to use viking units.
I'd like to know if somebody else tried this. It seems a fun thing to do and it's more varied then using just Vikings.